#include<stdio.h>
int  shu(int i)
{
    int shu=1;
    if(i==0||i==1)
    {
     shu=1;
    }
    else
   { 
    shu=((i-1)*i)/2+i;
   }
   return shu;
}
int main()
{
    printf("显示1+100的和%d\n",shu(100));
    printf("显示1+50的和%d\n",shu(50));
    return 0;
}